Early swimming pools built in South Africa were indoor structures, following the English design. They were often privately-owned enterprises, like the Camps Bay pool built in 1904, and the Arthur Nathan pool of 1893 in Bloemfontein.
The perception of a 'sunny South Africa' belies the fact that most of the interior beyond the fold mountains of the escarpment is over 1700m above sea level (Johannesburg - 1753m), where temperatures drop below freezing in winter, making unheated outdoor pools too cold for swimming for at least 6 months of the year. Suitable bodies of water for swimming were, and still are, in short supply. They can be divided between the natural - oceans, rivers and dams, and manufactured swimming pools. Recreational swimming was done in tidal pools, which were constructed in the rocks along the coast, predominantly near Cape Town and along the Natal south coast. Holidaymakers built them for safe swimming along the rugged coast, where swimming in the surf was dangerous.
As swimming became a competitive sport, and before swimming pools were built, events were held along the coast of False Bay from Muizenberg to Fish Hoek for the Gentry Cup race, in Cape Town dry dock and off the harbour pier, seen below is the 1926 Gordons Swimming club 2-mile race.

The rugged coastline is ideal for building tidal swimming pools. Many of South Africa's iconic swimming baths were originally built at tidal pools. These include the Sea Point pool, that was built in 1887, McArthur’s Baths in Port Elizabeth, the Rachael Finlayson pool in Durban and the Orient baths in East London. Today there are many tidal pools along the coast of South Africa, like the Dalebrook pool in False Bay below.
Besides swimming pools, swimmers often used rivers, dams, and the sea. During her visit in 1928, British swimmer Mercedes Gleitze swam in the Swartkops river near Port Elizabeth, the Buffalo in East London, the Modder in Bloemfontein, as well as Germiston Lake and Hartbeespoortdam. The Redhouse River Mile in Port Elizabeth has been held since 1928, although the Buffalo River Mile in east London has not continued. The most well-known swim in South Africa is the Robben Island crossing - while the world's largest open water race is the Midmar Dam Mile held in the Natal Midlands. Today there are many open water races held around the country.